Linear-motor paper feed



51s-13 SR biElAE'iEH HUUEQ rwmz: 2w831i3l April 15, 1958 H. J. KLOTZ 2,831,131

LINEAR-MOTOR PAPER FEED Filed Dec. 20, 1955 mmmmmmmmmmmummmmnfi 20 UUUEIUUEHIUUEIUDDUUDD FIG. 1.

I MAIN WINDING U" U 1613!: 19 2 0 18 2 4+4 Fla 2 Fla 3 FIG. 4: HERMAN J. KLOTZ AGENT LINEAR-MOTOR PAPER FEED Herman I. Klotz, Endicott, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application December 20, 1955, Serial No. 554,242

7 Claims. (Cl. 310 -13) This invention relates to an improvement in the feeding of paper sheets, record cards, and the like, and is particularly directed to the application of a linear motor to furnish the mechanical energy required to efiect such feeding.

In accordance with the preferred embodiment of the invention, a record card is positioned to feed on a pair of parallel trackbars. The record card has arranged on its surface, a pair of non-magnetic conducting strips and moves in a slot formed between the trackbars and a pair of wound magnetizable stator members. The stator members extend along the entire useful length of the trackbars and serve as the primary members of the linear motor with the record card serving as the secondary or armature member. Means are provided for energizing the stator windings to produce a traveling field which acts on the record card.

The use of polyphase apparatus, such as linear motors, for translating electrical into mechanical energy is well known and has been applied to numerous devices such as sliding doors, railway cars and catapult equipment. The main object of the present invention is to extend the use of the linear motor principle for the first time into the paper feeding art and accordingly an improved paper feed has been developed which possesses certain desirable advantages.

For example, in the present arrangement the movement of the paper sheet or record card is effected solely by the traveling field in the stator windings and consequently there is no need for any moving mechanical parts in the make-up of the feed structure. It follows, then that the present feed is simple to construct with no critical mechanical adjustments necessary and that with no moving parts, other than the sheet itself, it is extremely quiet in operation.

Another important advantage of the present arrangement resides in the fact that there are no elements such as pressure rolls, sucker members, feed knives, or the like and consequently the sheet is not subjected to any damaging effects and wear on the sheet is negligible. As such, the present arrangement could be used advantageously where it is necessary to maintain the record sheet against a suitable gate for registration purposes.

A still further important advantage of the present invention resides in the fact that it possesses the desirable feature of being able to impart a quick start to a record sheet at rest due to the fact that there is only the mass of the card to be moved. With the present invention the sheet is clutched quickly without having to wait for mechanical motions to occur.

Also, the present invention will work on all kinds of paper as well as record cards and can handle sheets of varying thickness with a minimum of adjustment. The direction of sheet movement can be easily reversed simply by reversing the input to one of the stator windings.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawing, which discloses, by way of 2,831,131 Patented Apr. 15, 1958 example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawing:

Fig. 1 is a view of a record card with non-magnetic conductive strips applied thereto according to the preferred embodiment of the present invention.

Fig. 2 illustrates the application of the present invention to a record sheet.

Fig. 3 is a simple circuit diagram showing the manner in which the stator windings are excited.

Fig. 4 is a vertical sectional view taken on line 4-4 of Fig. 2, showing the manner in which a driving-force is imparted to the record sheet.

As shown in Fig. 2. the linear motor structure comprises two stationary primary members 11 and 12 each consisting of a laminated magnetizable core which is provided with winding-receiving slots 13 (Fig. 4) on its airgap face, these slots 13 being separated by teeth 14. As shown in Fig. 4, the slots 13 carry the winding conductors 15. These primary members with their airgap faces facing downward are positioned above a pair of laminated magnetizable stationary cores or trackbars 16, 17, which extend along the entire desired feed path and which serve to support and guide the paper or record sheet 18 as well as provide a path for the driving magnetic flux.

The primary members 11, 12, also extend along the entire desired feed path and are separated from the trackbars 16, 17 by a slot 19 within which the sheet is free to travel.

In the preferred embodiment of the invention the sheet to be fed takes the form of the well-known IBM record card 18 which is fed through record controlled machines to control accounting operations. However, it should be understood that many different kinds of paper sheets or forms of varying size and thickness could be fed just as well in the manner about to be described.

As shown in Fig. 1, the record card has deposited on its surface a pair of strips 20 of non-magnetic conducting material such as copper. These strips are shown extending the length of the card and parallel to the long edges for effecting feeding of the card along its long axis but, of course, they may also be arranged across the width of the card and parallel to the short edges for effecting feeding of the card along the shorter axis. The conducting strips extend through the slot 19 and provide two linear-motor airgaps 21 and 22 between the card and the respective primary members 11 and 12.

The record card with the conducting strips attached thus acts as a secondary or armature member of the linear motor. In general, many different types of alloys could be used for the conducting material of the armature member; however, in the present application where the area of conducting material has to be kept to a minimum due to the nature and size limitations of record sheets and the fact that the sheets themselves are nonconducting in nature it is desirable to choose an alloy of fairly low resistivity so that sufficient force or torque will be developed to move the sheet. In addition to copper, it was found that alloys such as aluminum, brass or tin could be satisfactorily used as conducting strips on the sheet. The strips may be a grid or squirrel-cage structure, as illustrated, or may be a solid plate. The grid type of strip is preferred due to its lighter weight and the greater utilization of induced currents which is obtained.

For the present application a two-pole single phase motor having the usual main and auxiliary windings placed in space quadrature was chosen for its simplicity and economy. To produce a moving or traveling field the currents exciting the two windings should be in time quadrature with their peaks occurring apart in time. As is well known, in single phase applications this is accomplished by introducing capacitance or inductance to one winding generally the auxiliary winding as shown in Fig. 3. The resultant polyphase condition, of course, has the effect of creating moving sine waves of flux which produce a traveling field which moves in the direction the sheet is to be fed. The rate of travel of the field is necessarily higher than the rate at which the sheet is to be moved and since the field is traveling faster than the sheet or record card 18, it sets up currents in the conducting strips 20 on the card which react with the field to exert a powerful moving force on the card. The card will move along the trackbars 16, 17, tending to approach a synchronous speed which would be identical with the speed of movement of the traveling field.

The manner in which the card is moved can be better understood by referring to Fig. 4. As shown, the card is positioned, by any suitable means, with the conducting strips 20 between the primary members 11, 12 and the cores 16, 17 and the short cross-legs of each strip placed beneath the windings 15 and between the stator teeth 14. The position the card is shown in Fig. 4 is merely illustrative and it is understood that the cross-legs of the strips need not necessarily be positioned directly beneath the windings. It is only necessary that the con ducting strips be placed within the stator field set up between the primary members 11, 12 and the cores 16, 17. The primary lap winding flux lines 23 are shown moving in counterclockwise fashion from the stator core 11 down through the left-hand stator teeth, the card, the core 16 and back up through the card and the righthand stator teeth. The flux lines 23 induce currents to fiow in the cross-legs 20 of the conducting or armature strip, the current going toward the observer in the legs 20a20c and away from the observer in legs 20d and 20e. As a result, the flux lines 24 are set up around each conductor leg and are moving in the direction as shown.

It will be noted that the flux lines 23 and 24 are moving in the same direction at the left of each conductor leg and are moving in opposite directions at the right of each leg. Therefore, there is a dense field set up on the left of each conductor leg and a weak field on the right which will result in a series of forces, such as indicated at P, which. push the conductor strip and card to the right away from the denser fields.

Thus, it can be seen that a powerful force may be developed by the field along the conductor strips which will move the strips and the relatively light card or record sheet attached thereto with great speed and efficiency. The two conducting strips balance the forces exerted on the card to keep it moving in a straight line.

In some cases it may be more desirable to use only one conductor strip running down the center of the sheet and a single stator, in which case suitable side guides could be provided to keep the sheet from skewing.

It will be understood that the details which have been given are intended only to illustrate the generic principle of applying a linear motor to the art of paper feeding. The details and structure necessary for installing the present invention on apparatus such as record card controlled accounting machines, for example, are believed to be within the skill of anyone engaged in the building of such apparatus.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. A paper feed device comprising a magnetizable trackbar extending the length of desired feed, a sheet positioned on said trackbar for movement thereon, said sheet having a strip of non-magnetic conducting material secured thereto and extending lengthwise in the direction of feed, an elongated linear-motor stator structure extending the entire length of the desired feed and comprising wound magnetizable primary members facing said trackbar and spaced from the latter by a slot within which said sheet moves, with a linear-motor airgap between said sheet and said primary members, said sheet and attached conductor strip constituting the armature of the linear motor, and means for energizing said primary windings to produce a traveling field for moving the conductor strip and attached sheet.

2. A paper feed device comprising magnetizable trackbars extending the length of desired feed, a sheet positioned on said trackbars for movement thereon, said sheet having strips of non-magnetic conducting material secured thereto and extending along said sheet and in the direction of feed, an elongated linear-motor stator structure extending the entire length of the desired feed and comprising wound magnetizable primary members facing said trackbars and spaced from the latter by a slot within which said sheet moves, with a linear-motor airgap between said sheet and said primary members, said sheet and attached conductor strips constituting the armature of the linear motor, and means for energizing said primary windings to produce a traveling field for moving the conductor strips and attached sheet.

3. The invention as defined in claim 2, characterized by strips of non-magnetic conducting material having a grid or squirrel-cage type of structure.

4. A paper feed device comprising a pair of magnetizable trackbars extending the length of desired feed, a sheet positioned on said trackbars for movement thereon, said sheet having strips of nonmagnetic conducting material secured thereto and arranged as elongated squirrelcage structures extending lengthwise along opposite edges of said sheet and in the direction of feed, an elongated linear-motor stator structure extending the entire length of the desired feed and comprising two rows of stator teeth and interposed wound magnetizable primary members facing said trackbars and spaced from the latter by a slot within which said sheet moves, with a linear-motor airgap between said sheet and said primary members, said sheet and attached conductor strips constituting the armature of the linear motor, and means for energizing said primary windings to produce a traveling field for moving the conductor strips and attached sheet.

5. A record member adapted to be fed under control of a linear motor comprising a sheet of paper having a strip of non-magnetic conducting material secured thereto and extending lengthwise in the direction of feed.

6. A record member adapted to be fed under control of a linear motor comprising a sheet of paper having strips of non-magnetic conducting material secured thereto and extending lengthwise along opposite edges of said sheet and in the direction of feed.

7. A record member adapted to be fed under control of a linear motor comprising a sheet of paper having a pair of strips of non-magnetic conducting material secured thereto and arranged as elongated squirrel-cage structures extending lengthwise along opposite edges of said sheet and in the direction of feed.

References Cited in the filc of this patent UNITED STATES PATENTS 782,312 Zehden Feb. 14, 1905 1,480,553 Hoff Jan. 15, 1924 2,039,770 Birdsell et a1. May 5, 1936 2,112,264 Bowles et al Mar. 29, 1938 

